What is marijuana?

Marijuana is the dried leaves and flowers of the Cannabis sativa or Cannabis indica plant. Stronger forms of the drug include high potency strains - known as sinsemilla (sin-seh-me-yah), hashish (hash for short), and extracts including hash oil, shatter, wax, and budder.

Of the more than 500 chemicals in marijuana, delta-9-tetrahydrocannabinol, known as THC, is responsible for many of the drug’s psychotropic (mind-altering) effects. It’s this chemical that distorts how the mind perceives the world.

The amount of THC in marijuana has increased over the past few decades. In the early 1990s, the average THC content in marijuana was about 3.74 percent. In 2013, it was almost 10 percent, and much higher in some products such as oils and other extracts (see below).1 Scientists do not yet know what this increase in potency means for a person’s health. It may cause users to take in higher amounts of THC – which could lead to greater health risks including increased risk of addiction, or they may adjust how they consume marijuana (by smoking or eating less) to compensate for the greater potency. There have been reports of people seeking help in emergency rooms with symptoms, including psychosis (having false thoughts or seeing or hearing things that aren't there), after consuming high concentrations of THC.

Marijuana Extracts

Smoking extracts and resins from the marijuana plant with high levels of THC is on the rise. There are several forms of these extracts, such as hash oil, budder, wax, and shatter. These resins have 3 to 5 times more THC than the plant itself. Smoking or vaping it (also called dabbing) can deliver dangerous amounts of THC to users, and has led some people to seek treatment in the emergency room. There have also been reports of people injured in fires and explosions caused by attempts to extract hash oil from marijuana leaves using butane (lighter fluid).

How is marijuana used?

Some people smoke marijuana in hand-rolled cigarettes called joints. Many use glass pipes, water pipes called bongs, or marijuana cigars called blunts (often made by slicing open cigars and replacing some or all of the tobacco with marijuana). To avoid inhaling smoke, some people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana into the vapor. A person then inhales the vapor, not the smoke. Some vaporizers use a marijuana liquid extract.Marijuana can also be brewed as tea or cooked into food, sometimes called edibles—such as brownies, cookies, or candy.

These concentrated extracts made from the marijuana plant should not be confused with “synthetic marijuana,” sometimes called “K2,” “Spice,” or “herbal incense.” These synthetic drugs are man-made chemicals similar to THC but often much stronger and very dangerous. Unlike marijuana, their use sometimes directly results in overdose deaths. Learn more about "synthetic marijuana”.

What happens to your brain when you use marijuana?

When marijuana is smoked or vaporized, THC quickly passes from the lungs into the bloodstream, which carries it to organs throughout the body, including the brain. Its effects begin almost immediately and can last from 1 to 3 hours. Decision making, concentration, and memory can be affected for days after use, especially in regular users.2 If marijuana is consumed in foods or beverages, the effects of THC appear later—usually in 30 minutes to 1 hour—and may last for many hours.

As it enters the brain, THC attaches to cells, or neurons, with specific kinds of receptors called cannabinoid receptors. Normally, these receptors are activated by chemicals similar to THC that occur naturally in the body. They are part of a communication network in the brain called the endocannabinoid system. This system is important in normal brain development and function.

Most of the cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana activates the endocannabinoid system, which causes the pleasurable feelings or "high" and stimulates the release of dopamine in the brain's reward centers, reinforcing the behavior. Other effects include changes in perceptions and mood, lack of coordination, difficulty with thinking and problem solving, and disrupted learning and memory.

Certain parts of the brain have a lot of cannabinoid receptors. These areas are the hippocampus, the cerebellum, the basal ganglia, and the cerebral cortex. (Learn more about these areas and how THC affects them.) As a result, marijuana affects these functions:

Learning and memory. The hippocampus plays a critical role in certain types of learning. Disrupting its normal functioning can lead to problems studying, learning new things, and recalling recent events. Chronic marijuana use disorder, that begins in adolescence, is associated with a loss of IQ points, as compared with people who don't use marijuana during their teen years.3 However, two recent twin studies suggest that this decline is related to other risk factors (e.g., genetics, family, and environment), not by marijuana use itself.4

Coordination. THC affects the cerebellum, the area of our brain that controls balance and coordination, and the basal ganglia, another part of the brain that helps control movement. These effects can influence performance in such activities as sports, driving, and video games.

Judgment. Since THC affects areas of the frontal cortex involved in decision making, using it can make you more likely to engage in risky behavior, such as unprotected sex or getting in a car with someone who’s been drinking or is high on marijuana.

What happens to your body when you use marijuana?

Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the bronchial passages (the pipes that let air in and out of your lungs) relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. While these and other effects seem harmless, they can take a toll on the body.

Increased heart rate. When someone uses marijuana, heart rate—normally 70 to 80 beats per minute—may increase by 20 to 50 beats per minute or, in some cases, even double. This effect can be greater if other drugs are taken with marijuana. The increased heart rate forces the heart to work extra hard to keep up.

Respiratory (lung and breathing) problems. Smoke from marijuana irritates the lungs, and can cause a chronic cough—effects similar to those from regular cigarettes. While research has not found a strong association between marijuana and lung cancer, many people who smoke marijuana also smoke cigarettes, which do cause cancer. And, some studies have suggested that smoking marijuana could make it harder to quit cigarette smoking.5

Increased risk for mental health problems. Marijuana use has been linked with depression and anxiety, as well as suicidal thoughts among adolescents. In addition, research has suggested that in people with a genetic risk for developing schizophrenia, smoking marijuana during adolescence may increase the risk for developing psychosis and for it developing at an earlier age. Researchers are still studying the relationship between these mental health problems and marijuana use.

Increased risk of problems for an unborn baby. Marijuana use during pregnancy is linked to lower birth weight and increased risk of behavioral problems in babies.6

6 The National Academies of Sciences, Engineering, and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice, Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington, DC, January 12, 2017. Available at http://nationalacademies.org/hmd/Reports/2017/health-effects-of-cannabis-and-cannabinoids.aspx.

Can you die if you use marijuana?

There are no reports of people fatally overdosing (dying) on marijuana alone. However, people can feel some very uncomfortable side effects, especially when using marijuana with high THC levels. There are reports of marijuana users seeking treatment in emergency rooms, reporting unease and shaking, anxiety, paranoia, or hallucinations, and in rare cases, extreme psychotic reactions. Learn more about drug overdoses among youth. However, marijuana use can increase risks for accidents and injuries (impacts of drugged driving are discussed below).

What are the other risks associated with marijuana use?

Reduced school performance. Students who smoke marijuana tend to get lower grades and are more likely to drop out of high school than their peers who do not use. The effects of marijuana on attention, memory, and learning can last for days or weeks.

Reduced life satisfaction. Research suggests that people who use marijuana regularly for a long time are less satisfied with their lives and have more problems with friends and family compared to people who do not use marijuana.

Impaired driving. Marijuana affects a number of skills required for safe driving—alertness, concentration, coordination, and reaction time—so it’s not safe to drive high or to ride with someone who’s been smoking. Marijuana makes it hard to judge distances and react to signals and sounds on the road. High school seniors who smoke marijuana are 2 times more likely to receive a traffic ticket and 65% more likely to get into an accident than those who don’t smoke.7 In 2017, 10.3% of 12th graders reported driving after using marijuana in the past two weeks.8 And combining marijuana with drinking even a small amount of alcohol greatly increases driving danger, more than either drug alone. Learn more about what happens when you mix marijuana and driving.

Use of other drugs. Most young people who use marijuana do not go on to use other drugs. However, those who use are more likely to use other illegal drugs. It isn’t clear why some people go on to try other drugs, but researchers have a few theories. The human brain continues to develop into the early 20s. Exposure to addictive substances, including marijuana, may cause changes to the developing brain that make other drugs more appealing. In addition, someone who uses marijuana is more likely to be in contact with people who use and sell other drugs, increasing the risk for being encouraged or tempted to try them.

Severe nausea and vomiting. Studies have shown that in rare cases, regular, long-term marijuana use can lead some people to have cycles of severe nausea, vomiting, and dehydration, sometimes requiring visits to the emergency room.

Is marijuana addictive?

Yes, marijuana can be addictive. Someone who regularly uses marijuana may continue to use it despite negative consequences in their life.

Approximately 10 percent of users may develop what is called a marijuana use disorder—problems with their health, school, friendships, family or other conflicts in their life. A serious substance use disorder is commonly called an addiction. The person can’t stop using marijuana even though it gets in the way of daily life.9 People who begin using marijuana before the age of 18 are 4–7 times more likely than adults to develop a marijuana use disorder.10

What causes one person to become addicted to marijuana while another does not depends on many factors—including their family history (genetics), the age they start using, whether they also use other drugs, their family and friend relationships, and whether they take part in positive activities like school or sports (environment). More research needs to be done to determine whether people who use marijuana for medical reasons are at the same risk for addiction as those who use it recreationally.

Watch the Swiss Cheese Model of Drug Addiction and learn why some people become who use drugs get addicted and others do not.

People who use marijuana may feel a mild withdrawal when they stop using the drug. Withdrawal symptoms may include:

irritability

sleeplessness

lack of appetite, which can lead to weight loss

anxiety

drug cravings

These effects can last for several days to a few weeks after drug use is stopped. Relapse (returning to the drug after you’ve quit) is common during this period because people may crave the drug to relieve these symptoms.

9 Hasin DS, Saha TD, Kerridge BT, et al. Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013. JAMA Psychiatry. 2015;72(12):1235-1242. doi:10.1001/jamapsychiatry.2015.1858.

How many teens use marijuana?

Marijuana is the most commonly used illicit drug in the United States by teens as well as adults. Recent public discussions about medical marijuana and the public debate over the drug’s legal status is leading to a reduced perception of harm among young people. In addition, some teens believe marijuana cannot be harmful because it is “natural.”11 But not all natural plant substances are good for you—tobacco, cocaine, and heroin also come from plants.

Below is a chart showing the percentage of teens who say they use marijuana.

What about medical marijuana?

The marijuana plant itself has not been approved as a medicine by the federal government. However, the plant contains chemicals—called cannabinoids—that may be useful for treating a range of illnesses or symptoms. Here are some samples of cannabinoids that have been approved or are being tested as medicines:

THC: The cannabinoid that can make you “high”—THC—has some medicinal properties. A synthetic formulation of THC, dronabinol, has been approved by the federal government to treat nausea, prevent sickness and vomiting from chemotherapy in cancer patients, and to increase appetite in some patients with AIDS.

CBD: Another chemical in marijuana with potential therapeutic effects is called cannabidiol, or CBD. CBD doesn’t have mind-altering effects and is being studied for its possible uses as medicine. For example, CBD oil is being studied as a possible treatment for seizures in children with severe epilepsy.

THC and CBD: A medication with a combination of THC and CBD is available in several countries outside the United States as a mouth spray for treating pain or the symptoms of multiple sclerosis.

It is important to remember that smoking marijuana can have side effects, making it difficult to develop as a medicine. For example, it can harm lung health, impair judgment, and affect memory. Side effects like this might outweigh its value as a medical treatment, especially for people who are not very sick. Another problem with smoking or eating marijuana plant material is that the ingredients can vary a lot from plant to plant, so it is difficult to get an exact dose. Until a medicine can be proven safe and effective, it will not be approved by the federal government. But researchers continue to extract and test the chemicals in marijuana to create safe medicines.

It is important to note that a growing number of states have legalized the marijuana plant’s use for certain medical conditions, and a smaller number have voted to legalize it for recreational use. So, in some cases, federal and state marijuana laws conflict. It is illegal to grow, buy, sell, or carry marijuana under federal law. The federal government considers marijuana a Schedule I substance—having no medicinal uses and high risk for misuse.

Chat Day Transcripts

1832500 Walter Johnson High School, Maryland:

How long does marijuana stay in your system?

Michele Rankin

Hi 1832500 - That's a tricky question - the short answer is it depends. The chemicals found in the MJ plant are called cannabinoids and are fat-soluble. They are stored in body fat and released from there over time, and how quickly they are released depends on many factors, including how much cannabis has been used over what period of time, how much body fat someone has, exercise patterns, diet and other factors.

CJ Walter Johnson High School, Maryland:

is weed bad

Michele Rankin

HI CJ!

Some research suggests that marijuana may have the potential to help treat some health conditions including pain, nausea, epilepsy, and others. But there hasn’t been enough research on the subject, and patients across the country are using marijuana strains and extracts that haven’t been fully tested or shown to be effective for their medical condition.

So far, 25 states and D.C. have passed laws to let people use marijuana with recommendations from their doctors (and sometimes by fulfilling other requirements, like having a medical marijuana license). The federal government has decided not to challenge those laws to any great extent. But people who buy marijuana in a state where it’s legal (for medicinal or recreational use) cannot take it across state lines into a state where it is notlegal. So it remains a confusing issue. But researchers are studying possible medical uses for marijuana and some of the chemicals it contains.

0566572 International Studies Preparatory Academy, Florida:

what are some of the consequences of poor drug quality

Dave Thomas

Good morning! First question of the day for me! That is a good question. If you get drugs on the street, it is really hard to know what you get, Sometimes, drug dealers "cut" or add stuff to the drugs, and who knows what they put in. It is a gamble, and depending on what is put in, all sorts of things could happen. And other times, one might get more of the drug (say opioids) then is expected. The result can include overdose.

Infographics

Monitoring the Future 2017 Survey Results

Published: December 12, 2017

This infographic of the NIH’s 2017 Monitoring the Future survey highlights drug use trends among the Nation’s youth for marijuana, alcohol, cigarettes, e-cigarettes (e-vaporizers), and prescription opioids.

Substance Use in Women and Men

Published: January 08, 2016

This infographic shows differences in substance use trends between women and men for marijuana use disorder, abuse of prescription pain medicines, treatment admissions for sleeping aid misuse, and nicotine cessation.

Teens Mix Prescription Opioids with Other Substances

Synthetic Marijuana Lands Thousands of Young People in the ER, Especially Young Males

Published: February 26, 2013

By gender, 14% of male and 8% of female high school seniors abused synthetic marijuana.

This publication is available for your use and may be reproduced in its entirety without permission from NIDA. Citation of the source is appreciated, using the following language: Source: National Institute on Drug Abuse; National Institutes of Health; U.S. Department of Health and Human Services.

Cite this article

The National Institute on Drug Abuse Blog Team. (). Marijuana. Retrieved from https://teens.drugabuse.gov/drug-facts/marijuana on

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